A Multicast Control Channel (MCCH) is a point-to-multipoint downlink channel in an Evolved Multimedia Broadcast and Multicast Service (eMBMS, also referred to as Long Term Evolution (LTE) MBMS) system over which control information generally including eMBMS service information and radio bearer related information is transmitted from the network side to a User Equipment (UE), where the eMBMS service information indicates eMBMS services available in a cell where the user equipment is located, and for each eMBMS service, the eMBMS service information may include a service ID (a service identifier), a session ID (a session identifier), a radio bearer releasing indicator and other information; and for one or more eMBMS services, the radio bearer related information describes information on a radio bearer and a point-to-multipoint bearer used in a served cell, and for each eMBMS service, the radio bearer related information may include the service ID, physical channel information, transmission channel information, and radio bearer information.
Position information of an MCCH is indicated from the network side over a Broadcast Control Channel (BCCH), and different user equipments correspond to different position information so that the user equipments can fetch information transmitted over the MCCHs at indicated positions and access corresponding services according to control information carried over the MCCHs.
A modification period and a repetition period are defined for an MCCH. The modification period is an integer multiple of the repetition period, and in each modification period, contents over the MCCH are transmitted repeatedly at an interval of the repetition period and are unchangeable in the modification period. Stated otherwise, if information carried over an MCCH is changed, the changed information can be transmitted only after the next modification period is started. Since contents carried over an MCCH in the same modification period are transmitted repeatedly at an interval of a repetition period, a UE will not continue with monitoring any more information transmitted over the MCCH after fetching the information over the MCCH in the same modification period.
When information carried over an MCCH is changed, for example, when an eMBMS service is changed, or radio bearer information is changed, a user equipment has to be indicated from the network side to acquire the new changed information carried over the MCCH in time, that is, an MCCH change notification has to be transmitted from the network side to the user equipment, and the user equipment will monitor the MCCH and acquire the new changed information upon reception of the MCCH change notification.
In the prior art, an MCCH change notification is transmitted from the network side to a user equipment in the following two methods.
In a first method of the prior art, an MCCH change notification is carried in a paging information packet transmitted to a user equipment.
Specifically, in the prior art, user equipments in an eMBMS system include user equipments receiving an eMBMS service and user equipments receiving only a unicast service, both types of user equipments monitor paging information in their own paging periods. When the information carried over an MCCH is changed, a paging message including an MCCH change notification indication is transmitted from the network side to the user equipments, and a P-RNTI corresponding to the paging message is transmitted over a corresponding Physical Downlink Control Channel (PDCCH); and the user equipments can receive the paging message upon detection of the P-RNTI, parse the paging message according to the P-RNTI, acquire the MCCH change notification and fetch the changed information carried over the MCCH according to the MCCH change notification.
For example, if the modification period of the MCCH is 10240 milliseconds (ms) and the paging period of a specific user equipment is 320 ms, that is, the user equipment receives the paging information in a period of 320 ms, a modification period includes 32 paging periods in which an MCCH change can be notified.
However, since the MCCH change notification is transmitted to all the user equipments in the eMBMS system, that is, the user equipments receiving an eMBMS service can not be distinguished at the network side from the user equipments receiving only a unicast service, the user equipments receiving only a unicast service will also parse the paging information packet including the MCCH change notification upon detection of the P-RNTI, as a result of which it is possible that the paging information packet is not a true paging packet but just a paging information packet including the MCCH change notification which is not required for the user equipments receiving only a unicast service, so this method may degrade the performance of the user equipments receiving only a unicast service.
In a second method of the prior art, an MCCH change notification is carried over a PDCCH.
When information carried over an MCCH is changed, a specific Radio Network Temporary Identifier (RNTI), e.g., a Multimedia-Radio Network Temporary Identifier (M-RNTI), may be transmitted at a paging occasion from the network side over a PDCCH. A user equipment receiving an eMBMS service becomes awake in its own paging period and monitors the specific RNTI (e.g., M-RNTI) over the PDCCH. If it is detected that the M-RNTI is carried over the PDCCH, it indicates that the information over the MCCH is changed, and the user equipment will further monitor the MCCH and acquire the new information.
However, there is a limited space over the PDCCH, and when the specific RNTI is transmitted at a paging occasion of the user equipment from the network side to the user equipment along with other network identifiers, e.g., an RA-RNTI, an SI-RNTI, and a P-RNTI, the PDCCH may be congested by the information so that the specific RNTI may be processed in error and thus fail to be detected correctly by the user equipment and consequently the user equipment may miss the modified contents over the MCCH and fail to receive correctly an e-MBMS service. Furthermore, since a paging occasion may vary from one user equipment to another, a base station has to transmit a specific RNTI frequently and repeatedly, thus making the notification inefficient.